In laser-beam machining, a laser beam produced by a laser oscillator is deflected by a beam bender and then focused onto a workpiece by a lens. The angle of the beam bender is adjusted by angularly adjusting the mirror holder with three or four micrometers.
The angular adjustment of the mirror holder requires a lot of skilled work. Even if the angle of the mirror holder is adjusted, the bender mirror may be positionally displaced, thus displacing a spot which is irradiated by a laser beam defected by the bender mirror. It has been very difficult to adjust both the angle and position of the bender mirror with accuracy.